The present invention relates generally to reflector antenna systems, and more particularly, to a shaped reflector antenna system for use on a communication satellite.
The assignee of the present invention deploys communication satellites containing communications systems. Gregorian reflector antenna systems are typically used on such communication satellites. Although the assignee of the present invention has investigated numerous antenna configurations for use on satellites that it has developed, the use of two types of shaped reflector antenna systems for reducing the cross polarization level on a satellite has heretofore not been addressed.
Accordingly, it is an objective of the present invention to provide for a shaped reflector antenna system configuration for use on a communication satellite to improve the communication system performance.
To accomplish the above and other objectives, the present invention provides for a shaped reflector antenna system configuration for use on a communication satellite. The present invention addresses types and arrangements of shaped reflector antennas that are used in the shaped reflector antenna system used on the communication satellite to improve the communication system performance.
An exemplary antenna system comprises a plurality of shaped reflector antenna types. A first one of the antenna types is a diverged shaped reflector antenna and a second one of the antenna types is a converged shaped reflector antenna. Each of the shaped reflector antennas comprise a main reflector, a subreflector, and at least one feed horn. The feed horn illuminates the subreflector with RF energy in the shape of a feed cone that is reflected to the main reflector.
In the antenna system, the direction of RF energy propagation emitted by each of the shaped reflector antennas is in a direction that is generally different from a direction defined by a vector between a predetermined vertex and focal point associated with the respective shaped reflector antenna. In a specific embodiment, the direction of the coverage for the diverged shaped reflector antenna is counterclockwise with respect to a direction defined by a vector between a predetermined vertex and focal point associated with the diverged shaped reflector antenna. The direction of the coverage for the converged shaped reflector antenna is clockwise with respect to a direction defined by a vector between a predetermined vertex and focal point associated with the converged shaped reflector antenna.
The shaped reflector antenna configurations described in the present invention exhibit a reduced cross polarization level, and thus will improve the performance of a communication system in which they are employed. The shaped reflector antenna system configuration is intended for use on an LS2020(trademark) satellite developed by the assignee of the present invention.